Tubular patent foramen ovale (PFO) closure device with catch system

ABSTRACT

Occluder devices for occluding an anatomical aperture, such as an atrial septal defect (ASD) or a patent foramen ovale (PFO) comprise two sides connected by a central tube. The occluder devices are formed from a tube, which is cut to produce struts in each side. Upon the application of force, the struts deform into loops. The loops may be of various shapes, sizes, and configurations, and, in at least some embodiments, the loops have rounded peripheries. In some embodiments, at least one of the sides includes a tissue scaffold. The occluder devices include a catch system that maintains its deployed state in vivo. When an occluder device is deployed in vivo, the two sides are disposed on opposite sides of the septal tissue surrounding the aperture and the catch system is deployed so that the occluder device exerts a compressive force on the septal tissue and closes the aperture.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 11/395,718 filed Mar. 31, 2006, now issued as U.S. Pat. No.8,480,786; which is a continuation-in-part application of U.S.application Ser. No. 10/890,784 filed Jul. 14, 2004, now issued as U.S.Pat. No. 7,678,123; which claims the benefit under 35 USC §119(e) toU.S. Application Ser. No. 60/486,992 filed Jul. 14, 2003, now expired.The disclosure of each of the prior applications is considered part ofand is incorporated by reference in the disclosure of this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an occlusion device for theclosure of physical anomalies, such as an atrial septal defect, a patentforamen ovale, and other septal and vascular defects.

2. Background Information

A patent foramen ovale (PFO), illustrated in FIG. 1, is a persistent,one-way, usually flap-like opening in the wall between the right atrium11 and left atrium 13 of the heart 10. Because left atrial (LA) pressureis normally higher than right atrial (RA) pressure, the flap usuallystays closed. Under certain conditions, however, right atrial pressurecan exceed left atrial pressure, creating the possibility that bloodcould pass from the right atrium 11 to the left atrium 13 and bloodclots could enter the systemic circulation. It is desirable that thiscircumstance be eliminated.

The foramen ovale serves a desired purpose when a fetus is gestating inutero. Because blood is oxygenated through the umbilical cord, and notthrough the developing lungs, the circulatory system of the fetal heartallows the blood to flow through the foramen ovale as a physiologicconduit for right-to-left shunting. After birth, with the establishmentof pulmonary circulation, the increased left atrial blood flow andpressure results in functional closure of the foramen ovale. Thisfunctional closure is subsequently followed by anatomical closure of thetwo over-lapping layers of tissue: septum primum 14 and septum secundum16. However, a PFO has been shown to persist in a number of adults.

The presence of a PFO is generally considered to have no therapeuticconsequence in otherwise healthy adults. Paradoxical embolism via a PFOis considered in the diagnosis for patients who have suffered a strokeor transient ischemic attack (TIA) in the presence of a PFO and withoutanother identified cause of ischemic stroke. While there is currently nodefinitive proof of a cause-effect relationship, many studies haveconfirmed a strong association between the presence of a PFO and therisk for paradoxical embolism or stroke. In addition, there issignificant evidence that patients with a PFO who have had a cerebralvascular event are at increased risk for future, recurrentcerebrovascular events.

Accordingly, patients at such an increased risk are considered forprophylactic medical therapy to reduce the risk of a recurrent embolicevent. These patients are commonly treated with oral anticoagulants,which potentially have adverse side effects, such as hemorrhaging,hematoma, and interactions with a variety of other drugs. The use ofthese drugs can alter a person's recovery and necessitate adjustments ina person's daily living pattern.

In certain cases, such as when anticoagulation is contraindicated,surgery may be necessary or desirable to close a PFO. The surgery wouldtypically include suturing a PFO closed by attaching septum secundum toseptum primum. This sutured attachment can be accomplished using eitheran interrupted or a continuous stitch and is a common way a surgeonshuts a PFO under direct visualization.

Umbrella devices and a variety of other similar mechanical closuredevices, developed initially for percutaneous closure of atrial septaldefects (ASDs), have been used in some instances to close PFOB. Thesedevices potentially allow patients to avoid the side effects oftenassociated with anticoagulation therapies and the risks of invasivesurgery. However, umbrella devices and the like that are designed forASDs are not optimally suited for use as PFO closure devices.

Currently available septal closure devices present drawbacks, includingtechnically complex implantation procedures. Additionally, there are notinsignificant complications due to thrombus, fractures of thecomponents, conduction system disturbances, perforations of hearttissue, and residual leaks. Many devices have high septal profile andinclude large masses of foreign material, which may lead to unfavorablebody adaptation of a device. Given that ASD devices are designed toocclude holes, many lack anatomic conformability to the flap-likeanatomy of PFOs. Thus, when inserting an ASD device to close a PFO, thenarrow opening and the thin flap may form impediments to properdeployment. Even if an occlusive seal is formed, the device may bedeployed in the heart on an angle, leaving some components insecurelyseated against the septum and, thereby, risking thrombus formation dueto hemodynamic disturbances. Finally, some septal closure devices arecomplex to manufacture, which may result in inconsistent productperformance.

The present invention is designed to address these and otherdeficiencies of prior art septal closure devices.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a device for occluding anaperture in septal tissue, including a first side adapted to be disposedon one side of the septal tissue and a second side adapted to bedisposed on the opposite side of the septal tissue. The first and secondsides are adapted to occlude the aperture upon deployment of the deviceat its intended delivery location. The device also includes a catchsystem that maintains the configuration of the device once it has beendeployed.

According to some embodiments, the catch system reduces and maintainsthe axial length of the device. Also, varied constructions could be usedto maintain the axial dimension of the device. In one form, catchelements such as, e.g., balls, attached to a delivery wire could be usedto maintain the axial dimension of the device. In a differentconstruction, a locking mechanism could be used. Preferably, if alocking mechanism is used, it secures both sides of the device in thelocked position with a single locking element.

According to at least some embodiments, the device is formed from atube. According to some embodiments, the tube includes a materialselected from the group consisting of metals, shape memory materials,alloys, polymers, bioabsorbable polymers, and combinations thereof. Inparticular embodiments, the tube includes a shape memory polymer.According to some embodiments, the device is formed by cutting the tube.

According to some embodiments, at least one of the first and secondsides of the device includes a tissue scaffold. According to someembodiments, the tissue scaffold includes a material selected from thegroup consisting of polyester fabrics, Teflon-based materials,polyurethanes, metals, polyvinyl alcohol (PVA), extracellular matrix(ECM) or other bioengineered materials, synthetic bioabsorbablepolymeric scaffolds, collagen, and combinations thereof. In particularembodiments, the tissue scaffold includes nitinol.

According to some embodiments, the first and second sides of the deviceare connected by a central tube. According to some embodiments, thecentral tube is positioned so as to minimize distortion to the septaltissue surrounding the aperture. In particular embodiments, the centraltube is positioned at an angle θ from the second side, and the angle θis greater than 0 degrees and less than about 90 degrees.

In another aspect, the present invention provides a device for occludingan aperture in septal tissue, including a first side adapted to bedisposed on one side of the septal tissue and a second side adapted tobe disposed on the opposite side of the septal tissue. The first andsecond sides are adapted to occlude the defect when the device isdeployed at its intended delivery location. Each of the first and secondsides includes loops. The device further includes a catch system thatmaintains the configuration of the device once it has been deployed. Theloops of the first and second sides and the catch system cooperate toprovide a compressive force to the septal tissue surrounding theaperture.

According to some embodiments, each of the first and second sidesincludes at least two loops. In particular embodiments, each of thefirst and second sides includes four or six loops. Of course, the mostdesirable number of loops on each side will depend on a variety ofanatomical and manufacturing factors.

According to some embodiments, the device also includes a central tubethat connects the first and second sides. According to some embodiments,the central tube is positioned so as to minimize distortion to theseptal tissue surrounding the aperture. In particular embodiments, thecentral tube is positioned at an angle θ from the second side, and theangle θ is greater than 0 degrees and less than about 90 degrees.

According to some embodiments, the device is formed from a tube.According to some embodiments, the tube includes a material selectedfrom the group consisting of metals, shape memory materials, alloys,polymers, bioabsorbable polymers, and combinations thereof. Inparticular embodiments, the tube includes nitinol. In particularembodiments, the tube includes a shape memory polymer.

According to some embodiments, at least one of the first and secondsides further includes a tissue scaffold. According to some embodiments,the tissue scaffold includes a material selected from the groupconsisting of polyester fabrics, Teflon-based materials, polyurethanes,metals, polyvinyl alcohol (PVA), extracellular matrix (ECM) or otherbioengineered materials, synthetic bioabsorbable polymeric scaffolds,collagen, and combinations thereof. In particular embodiments, thetissue scaffold includes nitinol.

According to some embodiments, each of the loops includes a rounded edgeat its periphery to minimize trauma to the septal tissue. In particularembodiments, the outer periphery of the device is circular.

In still another aspect, the present invention provides a method ofmaking a device for occluding an aperture in septal tissue, includingproviding a tube having first and second ends and upper and lowerportions, cutting at least four axially-extending openings in the upperportion of the tube, cutting at least four axially-extending openings inthe lower portion of the tube. The openings in the upper and lowerportions are separated by a central portion of the tube.

According to some embodiments, the tube includes a material selectedfrom the group consisting of metals, shape memory materials, alloys,polymers, bioabsorbable polymers, and combinations thereof. Inparticular embodiments, the tube includes a shape memory polymer.

In yet another aspect, the present invention provides a method ofoccluding an aperture in septal tissue, including providing a tubehaving first and second ends and upper and lower portions in a deliverysheath. The tube includes at least four axially-extending openings inits upper portion and at least three axially-extending openings in itslower portion. The openings in the upper and lower portions areseparated by a central portion of the tube. The deliver sheath isinserted into a right atrium of a heart, through the aperture in theseptal tissue, and into the left atrium of the heart. The first end andthe upper portion of the tube are deployed into the left atrium. Thesheath is then retracted through the aperture and into the right atriumof the heart, where the second end and the lower portion of the tube aredeployed into the right atrium. The sheath is then withdrawn from theheart. Of course, a catch system could be used to secure the device in adelivered (expanded) state. The catch system may have any or all thecharacteristics described in the specification. Further, other types ofcatch systems could be used to hold the device in the delivered state.

According to some embodiments, a force is applied to each of the firstand second ends in an axial direction such that the axial length of thetube is reduced. The force applied to the first end is in a directionopposite to that of the force applied to the second end.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a human heart including variousseptal defects.

FIGS. 2A-2D are isometric views of an embodiment of an occluderaccording to the present invention.

FIGS. 2E-2H are isometric views of an embodiment of an occluderaccording to the present invention.

FIGS. 2I-2K are isometric views of occluders according to variousembodiments of the invention.

FIGS. 2L and 2M are side and top views, respectively, of an alternateembodiment of an occluder according to the present invention.

FIGS. 3A-3C are front elevational, side, and cross-sectional views,respectively, of the occluder of FIGS. 2A-2D.

FIGS. 4A-4B are front elevational and side views, respectively, ofanother embodiment of an occluder according to the present invention.

FIGS. 5A-5B are front and side views, respectively, of still anotherembodiment of an occluder according to the present invention.

FIGS. 6A-6E are isometric views of one embodiment of a catch systemaccording to the present invention

FIGS. 7A-7C are side views of another embodiment of a locking mechanismaccording to the present invention.

FIGS. 8A-8C are isometric views of yet another embodiment of an occluderaccording to the present invention.

FIGS. 9A-9H are side views of one method for delivering an occluderaccording to the present invention to a septal defect.

FIGS. 10A-10D are side views of one method for retrieving an occluderaccording to the present invention from a septal defect.

FIG. 11 is a side view of an embodiment of the occluder of the presentinvention.

FIG. 12 is an isometric view of an embodiment of the occluder of thepresent invention.

FIG. 13 is a side view of the occluder of FIGS. 2I-2K deployed in vivo.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a device for occluding an aperture withinbody tissue. This device relates particularly to, but is not limited to,a septal occluder made from a polymer tube. In particular and asdescribed in detail below, the occluder of the present invention may beused for closing an ASD or PFO in the atrial septum of a heart. Althoughthe embodiments of the invention are described with reference to an ASDor PFO, one skilled in the art will recognize that the device andmethods of the present invention may be used to treat other anatomicalconditions. As such, the invention should not be considered limited inapplicability to any particular anatomical condition.

FIG. 1 illustrates a human heart 10, having a right atrium 11 and a leftatrium 13 and including various anatomical anomalies 18 a and 18 b. Theatrial septum 12 includes septum primum 14 and septum secundum 16. Theanatomy of the septum 12 varies widely within the population. In somepeople, septum primum 14 extends to and overlaps with septum secundum16. The septum primum 14 may be quite thin. When a PFO is present, bloodcould travel through the passage 18 a between septum primum 14 andseptum secundum 16 (referred to as “the PFO tunnel”). Additionally oralternatively, the presence of an ASD could permit blood to travelthrough an aperture in the septal tissue, such as that schematicallyillustrated by aperture 18 b.

The term “bioabsorbable,” as used in this application, is alsounderstood to mean “bioresorbable.”

In this application, “distal” refers to the direction away from acatheter insertion location and “proximal” refers to the directionnearer the insertion location.

Referring to occluder 20, distal side 30 and proximal side 40 areconnected by central tube 22. As illustrated, e.g., in FIGS. 9 and 10the central tube 22 is an uncut central part of the tube used to formoccluder 20. As described below, the entire tube is indicated byreference numeral 25. As shown in FIGS. 9 and 10, the occluder 20 may beinserted into the septal tissue 12 to prevent the flow of blood throughthe aperture 18 a, e.g., the occluder may extend through the PFO tunnelsuch that the distal side 30 is located in the left atrium 13 and theproximal side 40 is located in the right atrium 11. Additionally oralternatively, the occluder 20 may be inserted into the septal tissue 12so as to prevent the flow of blood through the aperture 18 b, e.g., theoccluder may extend through the ASD such that the distal side 30 islocated in the left atrium 13 and the proximal side 40 is located in theright atrium 11. As used in this application, unless otherwiseindicated, the term “aperture 18” refers to any anatomical anomaly thatmay be treated by use of occluder 20, such as PFO 18 a or ASD 18 b.

The occluder 20 is constructed of one or more metal or polymer tube(s),referred to collectively as “tube” 25. Tube 25 includes slits 31 and 41(or 231 and 241), which are formed using an etching or cutting processthat produces a particular cutting pattern on tube 25. For example, asshown in FIG. 2K, slits 31 (or 231) are cut along the axial length ofthe upper half of tube 25 using a cutting tool, e.g., a razor blade.According to some embodiments of the present invention and as shown inFIG. 2K, slits 31 (or 231) are cut without removing any significantamount of material from tube 25, i.e., the formation of slits 31 (or231) does not significantly reduce the overall volume of tube 25.According to other embodiments of the present invention, slits 31 (or231) are formed by cutting material out of tube 25 such that the volumeof tube 25 is reduced. Both ends of each of slits 31 are rounded so asto relieve stresses at the axial ends of the slits 31. This preventsslits 31 from lengthening due to cyclic stresses present in a beatingheart and the resultant material fatigue. In those embodiments whereslits 31 are cut without removing any significant amount of materialfrom tube 25, rounded ends or holes 33 may be produced by burning holesat both ends of each of slits 31. In those embodiments where slits 31are formed by cutting material out of tube 25, rounded ends 33 may beformed during the cutting process. The size of rounded ends 33 may varydepending upon the dimensions of tube 25 and the amount of stressrelease required by the deformation.

FIGS. 2D and 2H illustrate exemplary occluder 20 formed from a tube 25,according to some embodiments of the present invention. Configuration ofthe occluder 20 is determined by the cutting pattern on tube 25. Forexample, and as shown in FIGS. 2A, 2B-2D, and 3A-3C, petal-shaped loops32, 42 (FIGS. 2A-2D and FIG. 3A) are produced by cutting slits 31 in thedistal side 30 of tube 25, and cutting slits 41 in the proximal side 40of tube 25 according to the cutting pattern shown in FIG. 2A. As shownin FIG. 2B, the distal side 30 of tube 25 is cut in half from a centerportion 22 to a distal distance to form half sections 91 a and 91 b. Thehalf sections 91 a and 91 b are further cut to a proximal distance fromthe distal end 39 into quarter sections 92 a, 93 a, 92 b, and 93 b. Thecuts are discontinued and quarter sections 92 a and 92 b form halfsection 94 a at end 39, and quarter sections 93 a and 93 b form halfsection 94 b at end 39. Upon application of force F_(d) to end 39,struts bow and twist outward to form petal-shaped loops 32 in distalside 30, as shown in FIGS. 2C-2D. The movement of the struts duringdeployment is such that the struts rotate in an orthogonal planerelative to the axis of the device. Central tube 22 may be constrainedduring the application of force F_(d), or any combination of forcessufficient to reduce the axial length of the tube 25 may be applied. Oneend of each of petal-shaped loops 32 originates from central tube 22,while the other end originates from end 39 (FIGS. 2B-2C and FIG. 3A).Petal-shaped loops 42 may be formed in proximal side 40 of tube 25, asshown in FIGS. 2B-2D, using the same cutting pattern described above.

Given that the surface of occluder 20 will contact septal tissue 12 onceit is deployed in vivo, slits 31 and 41 are cut so as to prevent theformation of sharp, potentially damaging edges along their length. Forexample, a heated cutting tool may be used to cut slits 31 and 41 suchthat the material of tube 25 melts slightly when placed in contact withthe cutting tool. Such melting rounds the edges of the sections. Lasersmay also be used to cut slits 31 and 41. According to this process, theedges of loops 32 and 42 formed by the cutting of slits 31 and 41 areblunted (due to melting) to prevent tissue damage in vivo. One skilledin the art will recognize that same considerations and techniques alsoapply to slits 231 and 241.

The tube(s) 25 forming occluder 20 includes a biocompatible metal orpolymer. In at least some embodiments, the occluder 20 is formed of abioabsorbable polymer, or a shape memory polymer. In other embodiments,the occluder 20 is formed of a biocompatible metal, such as a shapememory alloy (e.g., nitinol). The thermal shape memory and/orsuperelastic properties of shape memory polymers and alloys permit theoccluder 20 to resume and maintain its intended shape in vivo despitebeing distorted during the delivery process. In addition, shape memorypolymers and metals can be advantageous so that the structure of thedevice assists in compressing the PFO tunnel closed. Alternatively, oradditionally, the occluder 20 may be formed of a bioabsorbable metal,such as iron, magnesium, or combinations of these and similar materials.Exemplary bioabsorbable polymers include polyhydroxyalkanoatecompositions, for example poly-4-hydroxybutyrate (P4HB) compositions,disclosed in U.S. Pat. No. 6,610,764, entitled PolyhydroxyalkanoateCompositions Having Controlled Degradation Rate and U.S. Pat. No.6,548,569, entitled Medical Devices and Applications ofPolyhydroxyalkanoate Polymers, both of which are incorporated herein byreference in their entirety.

The cross-sectional shape of tube 25 may be circular or polygonal, forexample square, or hexagonal. The slits 31 and 41 (or 231 and 241) maybe disposed on the face of the polygon (i.e., the flat part) or on theintersection of the faces.

The tube 25 can be extruded or constructed of a sheet of material androlled into a tube. The sheet of material could be a single ply sheet ormultiple ply. The slits that form the struts could be cut or stampedinto the tube prior to rolling the tube to connect the ends to form anenclosed cross section. Various geometrical cross sections are possibleincluding circular, square, hexagonal and octagonal and the joint couldbe at the vertex or along the flat of a wall if the cross section is ofa particular geometery. Various attachment techniques could be used tojoin the ends of the sheet to form a tube, including welding, heatadhesives, non-heat adhesives and other joining techniques suitable forin-vivo application.

The surface of tube 25 may be textured or smooth. An occluder 20 havinga rough surface produces an inflammatory response upon contact withseptal tissue 12 in vivo, thereby promoting faster tissue ingrowth,healing, and closure of aperture 18 a (shown in FIG. 1). Such a roughsurface may be produced, for example, by shaving tube 25 to producewhiskers along its surface. For example, central tube 22 may includesuch whiskers. Additionally or alternatively, the surface of tube 25 maybe porous to facilitate cell ingrowth.

The distal side 30 of the occluder 20 (also called the “anchor portion”)is shown in FIGS. 2C and 2D. The distal side 30 includes four loops 32a, 32 b, 32 c, and 32 d (collectively referred to as loops 32). Aspreviously described, each of loops 32 a-32 d are formed bycorresponding cut sections 92 b, 93 b, 92 a, 93 a, produced by cuttingslits 31. The application of force F_(d) to end 39 of tube 25 brings theaxial ends of slits 31 together such that struts bow and twist outwardlyto form loops 32 of distal side 30 (FIGS. 2B-2C). Central tube 22 may beconstrained during the application of force F_(d). One skilled in theart will recognize that any combination of forces sufficient to reducethe axial length of the tube 25 would be sufficient to deploy the distalside 30 of occluder 20.

As illustrated, the loops 32 are evenly distributed about central tube22 and end 39. Thus, when the distal side 30 includes four loops 32 (asshown in FIGS. 2C and 2D), the four slits 31 are spaced 90 degreesradially apart. Similarly, when the distal side 30 includes six loops32, the six slits 31 are spaced 60 degrees radially apart. The anglebetween radially equally-spaced is determined by the formula(360/n_(d)), where n_(d) is the total number of loops 32.

Although the distal side 30 of the occluder 20 shown in FIG. 3A includesfour loops 32, occluders according to the present invention may includeany number of loops 32 necessary for a given application. In particularembodiments, the distal side 30 of occluder 20 includes six loops 32(FIG. 4A). Occluders having between four and ten loops 32 may be formedwithout requiring significant adjustments in the processes described inthis application. However, occluders having less than four or more thanten loops 32 may be complicated to manufacture and difficult deliverthrough the vasculature.

Regardless of the number of loops included in distal side 30 anddepending upon the material used to form occluder 20, the outerperimeter of loops 32 may vary. In at least some embodiments, the outerperimeter of loops 32 is rounded to provide an occluder 20 having asmooth, circular perimeter. As the number of loops 32 in the distal side30 of occluder 20 increases, it becomes desirable to round the outerperimeters of the loops 32 so as to prevent the infliction of trauma onthe surrounding septal tissue 12.

The proximal side 40 of the occluder 20, shown in side view in FIG. 2D,also includes four loops, 42 a, 42 b, 42 c, and 42 d (collectivelyreferred to as loops 42). As previously described, each of loops 42 a-42d are formed by corresponding cut sections, produced by cutting slits41. The application of force F_(p) to tip 44 of tube 25 brings the axialends of slits 41 together such that struts bow and twist outwardly toform loops 42 of proximal side 40 (FIGS. 2C-2D). Central tube 22 may beconstrained during the application of force F_(p). One skilled in theart will recognize that any combination of forces sufficient to reducethe axial length of the tube 25 would be sufficient to deploy theproximal side 40 of occluder 20. As described above for distal loops 32,the loops 42 are evenly distributed about central tube 22 and tip 44.Similarly, the angle between radially equally-spaced slits 41 in theproximal side 40 is determined by the formula (360/n_(d)), where n_(d)is the total number of loops 42.

Although the proximal side 40 of the occluder 20 shown in FIG. 2Dincludes four loops 42, one skilled in the art will recognize that theproximal side 40 of an occluder according to the present invention mayinclude any number of loops 42 required and suitable for a givenapplication. In particular embodiments, the proximal side 40 of occluder20 includes six loops 42 (FIG. 4A). Further, although as illustrated,distal side 30 and proximal side 40 both include four loops, there is norequirement that distal side 30 and proximal side 40 of occluder 20include the same number of loops. In fact, in particular applications,it may be advantageous to use an occluder 20 in which the distal side 30contains fewer loops than the proximal side 40, or vice versa.

It will be apparent to one skilled in the art that loops 32 and loops 42(or loops 232 and 242) do not have to be the same size. In oneembodiment, loops 32 (or 232) are larger in size than loops 42 (or 242).In another embodiment, loops 32 (or 232) are smaller in size than loops42 (or 242). Size of loops 32 and 42 (or 232 and 242) is determined bythe lengths of slits 31 and 41 (or 231 and 241), respectively.Therefore, absolute and relative lengths of slits 31 and 41 (or 232 and241) can be varied to achieve desired absolute and relative sizes ofloops 32 and 42 (or 232 and 242).

In at least some embodiments, illustrated in FIGS. 4A, loops 42 of theproximal side 40 are radially offset from loops 32 of the distal side 30to provide a better distribution of forces around the aperture 18 a.This can be achieved by making cuts to create slits 31 and 41 such thatthey are radially offset relative to each other. The maximum degree ofoffset will depend on the number of slits. In general, if slits areequally spaced, the maximum possible offset will be one half of theangle between the loops. For example, if distal side 30 (or proximalside 40) contains 4 slits (and therefore 4 loops), loops will be 90degrees apart (see the formula described above), thereby allowing formaximum degree of offset of one half of 90 degrees (which is 45 degrees)between loops 32 and loops 42. In a preferred form, when distal side 30(or proximal side 40) contains 4 slits (and therefore 4 loops), loops 42and loops 32 are offset by 45 degrees. In an alternative embodiment, thedegree of offset between loops 32 and 42 ranges from about 30 to about45 degrees.

FIGS. 2E-2H illustrate another embodiment of the invention, where theoccluder 20 is formed from a tube with loops 232 and 242, produced fromthe cutting pattern shown in FIG. 2E. In one embodiment, the proximalside 40 and the distal side 30 of occluder 20 each include eight loopsor petals. As shown in FIG. 2E, the distal portion 30 of the tube 25includes 8 slits 231 that form 8 extended segments of the tube that formthe distal loops or petals 232. As apparent from the figures, the slitsextend the entire distance of the distal portion 30 of the tube 25,i.e., between central tube 22 and distal end 39, so that the loops ofidentical cross-sections are formed. Upon application of force F_(d) todistal end 39, extended segments defined by slits 231 bow and twistoutward to form distal petals 232 in distal side 30 of the occluder 20.The movement of the segments during deployment is such that the segmentsrotate in an orthogonal plane relative to the axis of the device.Central tube 22 may be constrained during the application of forceF_(d), or any combination of forces sufficient to reduce the axiallength of the tube may be applied. One end of each of distal petals 232originates from central tube 22, while the other end originates fromdistal end 39. Proximal petals 242 may be formed in proximal portion 40,as shown in FIGS. 2E-2H, making slits 241 between central tube 22 andproximal tip 44, using the same cutting pattern described above andapplying force F_(p) or combination of forces sufficient to reduce theaxial length of the tube by allowing slits 241 to bow and twist outwardto form proximal petals 242 in proximal portion 40 of the occluder 20.One end of each of proximal petals 242 originates from central tube 22,while the other end originates from proximal tip 44. A catch system maytake a variety of forms, further non-limiting examples of which areprovided below in FIGS. 6A-6E. For example, as shown in FIGS. 2F and 2H,the catch system includes two catch elements, e.g., ball 133 and flange135′, operatively connected to delivery string 137.

One embodiment of the distal side 30 of the occluder 20 (also called the“anchor portion”) is shown in FIG. 2G and 2H. The distal side 30includes eight loops 232 a, 232 b, 232 c, 232 d, 232 e, 323 f, 232 g,and 232 h (collectively referred to as loops 232). As previouslydescribed, each of loops 232 a-232 h is produced by cutting slits 231.The application of force F_(d) to end 39 of tube 25 brings the axialends of slits 231 together such that struts bow and/or twist outwardlyto form loops 232 of distal side 30 (FIGS. 2F-2G). Central tube 22 maybe constrained during the application of force F_(d). One skilled in theart will recognize that any combination of forces sufficient to reducethe axial length of the tube 25 would be sufficient to deploy the distalside 30 of occluder 20.

As illustrated, the loops 232 are evenly distributed about central tube22 and end 39. Thus, when proximal side 30 includes eight loops 232 (asshown in FIGS. 2G and 2H), the eight slits 231 are spaced 45 degreesradially apart. The angle between radially equally-spaced slits 231 indistal side 30 is determined by the formula (360/n_(d)) where n_(d) isthe total number of loops 232.

The proximal side 40 of the occluder 20, shown in side view in FIG. 2H,also includes eight loops, 242 a, 242 b, 242 c, 242 d, 242 e, 242 f, 242g, and 242 h (collectively referred to as loops 242). As previouslydescribed, each of loops 242 a-242 h is produced by cutting slits 241.The application of force F_(p) to tip 44 of tube 25 brings the axialends of slits 241 together such that struts bow and twist outwardly toform loops 242 of proximal side 40 (FIGS. 2G-2H). Central tube 22 may beconstrained during the application of force F_(p). One skilled in theart will recognize that any combination of forces sufficient to reducethe axial length of the tube 25 would be sufficient to deploy theproximal side 40 of occluder 20. As described above for distal side 30,the loops 242 are evenly distributed about central tube 22 and tip 44.Similarly, the angle between radially equally-spaced slits 241 inproximal side 40 is determined by the formula (360/n_(d)) where n_(d) isthe total number of loops 242.

Although the distal side 30 and the proximal side 40 of the occluder 20,shown in FIG. 2H, each include eight loops 232 and 242, respectively,one skilled in the art will recognize that the distal side 30 andproximal side 40 of an occluder 20 according to the present inventionmay include any number of loops 232 and 242, respectively, requiredand/suitable for a given application. Further, although as illustrated,distal side 30 and proximal side 40 both include eight loops, there isno requirement that distal side 30 and proximal side 40 include the samenumber of loops. In fact, in particular applications, it may beadvantageous to use an occluder 20 in which distal side 30 containsfewer loops than proximal side 40, or vice versa.

It will be apparent to one skilled in the art that loops 232 and loops242 do not have to be the same size. In one embodiment, loops 232 arelarger in size than loops 242. In another embodiment, loops 232 aresmaller in size than loops 242. Size of loops 232 and 242 is determinedby the lengths of slits 231 and 241, respectively. Therefore, absoluteand relative lengths of slits 231 and 241 can be varied to achievedesired absolute and relative sizes of loops 232 and 242.

While loops 232 and 242, shown in FIGS. 2F-2H are illustrated asaligned, this does not have to be the case. In one embodiment, loops 232and 242 are radially offset from each other. This can be achieved bymaking cuts to create slits 231 and 241 such that they are radiallyoffset relative to each other. The maximum degree of offset will dependon the number of slits. In general, if slits are equally spaced, themaximum possible offset will be one half of the angle between the loops.For example, if distal side 30 (or proximal side 40) contains 8 slits(and therefore 8 loops), the loops will be 45 degrees apart (see theformula described above), thereby allowing for maximum degree of offsetof one half of 45 degrees, which is 22.5 degrees between loops 232 andloops 242. It is understood, that offset can be in either rotationaldirection (i.e., clockwise and counterclockwise). Therefore, in thisexample with 8 slits, an offset of 30 degrees is equivalent to an offsetof 7.5 degrees in the opposite direction.

The cutting pattern illustrated in FIG. 2E can be varied, as shown inFIGS. 2I-2K. According to one embodiment of the invention, the number ofslits 231 and 241 cut in the tube 25 can be changed according to thedesired number of loops 232 and 242 in the occluder 20 when deployed.The cross-sectional dimensions of loops 232 and 242 are determined bythe thickness of tube 25 and the distance between adjacent slits 231 and241. The length of slits 231 and 241 determines the length of loops 232and 242 and the radial dimensions of the deployed occluder 20. In thismanner, the dimensions of loops 232 and 242 can be controlled duringproduction of occluder 20. For example, as more material is removed fromtube 25 during the cutting process used to form slits 231 and 241, thethickness of loops 232 and 242 decreases. Moreover, any or all of slits231 and 241 can be cut such that thickness of loops 232 and 242 variesalong their length. In some embodiments, it may be desirable to havewider loops 232 and 242 at the location where the loops join tube 25 tocreate a sturdier device. Alternatively, it may be desirable to have awider portion elsewhere along the loops 232 and 242 such that occluder20 is predisposed to bend into a certain shape and arrangement. Forexample, the portion of loops 232 and 242 nearer central tube 22 may bethinner than the portion of loops 232 and 242 nearer end 39 and tip 44,respectively, to facilitate bending of the loops 232 and 242.

Slits 231 and 241, as shown in FIG. 2J, are cut axially along the lengthof tube 25. However, as one of skill in the art will recognize, slits231 and/or 241 may also be cut along other dimensions of tube 25. Forexample, as shown in FIG. 2I, slits 231 and 241 may be cut at an anglesuch that they are helically disposed on tube 25. Angled slits 231 and241 produce angled loops 232 and 242 during deployment. Further, slits231 and 241 need not be straight; for example, slits 231 and 241 may becut as zigzags, S-shaped slits, or C-shaped slits. One skilled in theart will be capable of selecting the angle for the slits 231 and/or 241and the loop 232 and 242 shape(s) appropriate for a given clinicalapplication. For example, when occluder 20 is formed from a polymer tube25, straight loops 232 and 242 may be preferable because they willimpart maximum stiffness to occluder 20. If the tube 25 is formed of astiffer material, the angled slits 231 and/or 241 may provide a moredesired stiffness to the occluder 20.

In one embodiment, the occluder 20 has loops according to FIGS. 2A-2D onone side and loops according to FIGS. 2E-2H on the other side. Forexample, occluder 20 may comprise loops 42 on the proximal side 40 andloops 232 on the distal side 30, or it may comprise loops 242 on theproximal side 40 and loops 32 on the distal side 30.

In one embodiment, for example as shown in FIG. 2H, each loop 242 and232 has some amount of twist, i.e., when the loop is formed, theproximal side of the loop is radially offset with respect to the distalside of the loop. Loops 242 and/or 232, however, need not have anytwist.

FIG. 2M, for example, illustrates an embodiment of the occluder withslits cut as illustrated in FIG. 2L. In this embodiment, neither loops32 nor loops 42 are twisted. It will be apparent to one skilled in theart that any combination of twisted and untwisted loops may be used.Furthermore, an occluder can have any combination of loops withdifferent bends and twists if desired.

In one embodiment, loops 32 (or 232) of distal side 30 are bent to formconcave loops, while loops 42 (or 242) of proximal side 40 are flat(FIG. 11). In this embodiment, the outermost portions of loops 42 (or242) of proximal side 40 oppose the outermost portions of the loops 32(or 232) of the proximal side 30, as described in more detail below,thereby creating a desirable opposing force that secures the occluder 20at its desired location in vivo. So configured, the opposing compressiveforces exerted by sides 30 and 40 on the septal tissue 12 followingdeployment of occluder 20 in vivo is advantageous in certaincircumstances, such as closing certain kinds of PFOs. In anotherembodiment, loops 42 (or 242 of the proximal side 40 are bent, whileloops 32 (or 232) of the distal side 30 are flat. In yet anotherembodiment, loops 42 (or 242) of the proximal side 40 and loops 32 (or232) of the distal side 30 are bent.

Whatever the number and shapes of loops 32 and 42 (or 232 and 242), theloops 32 and 42 (or 232 and 242) may be of varied sizes to facilitatedelivery of occlude 20, e.g., to improve collapsibility of the occluder20 or to enhance its securement at the delivery site. For example, loops32 and 42 (or 232 and 242) that are sized to better conform withanatomical landmarks enhance securement of the occluder 20 to the septaltissue 12 in vivo. As indicated above, the cross-sectional dimensions ofloops 32 and 42 (or 232 and 242) are determined by the thickness of tube25 and the distance between adjacent slits 31 and 41 (or 231 and 241).The length of slits 31 and 41 (or 231 and 241) determines the size ofloops 32 and 42 (or 232 and 242) and the radial extent of the deployedoccluder 20. In at least some embodiments, each of distal side 30 andproximal side 40 has a diameter in the range of about 10 mm to about 45mm, with the particular diameter determined by the size of theparticular defect being treated. In particular embodiments, the diameterof distal side 30 will be different than that of proximal side 40 so asto better conform to the anatomy of the patient's heart.

According to one embodiment of the invention, the loops of the occluderare formed by struts as illustrated in FIG. 2B. Sections 91 a, 91 b, 92a, 92 b, 93 a, 93 b, 94 a, and 94 b are of equal distance, being about ⅓the length of distal side 30 (i.e., the distance between central tube 22and end 39) of the tube 25. According to another embodiment of theinvention, other lengths of sections can be used to produce advantageousresults. In general, the longer the length of the hemispherical struts,such as half sections 91 a, 91 b, 94 a, and 94 b, the stiffer theoccluder will be. The longer the length of the quarter (as shown)struts, such as half sections 92 a, 92 b, 93 a, and 93 b, the less stiffthe occluder will be. In general, the hemispherical cut (one of the two)may be 20-40% of the overall length of the distal side (or proximalside) the tube. Specifically, the hemispherical cuts could be 40% of theoverall length of the distal side (or proximal side) and then thequarter cut could be 20% of the overall length of the distal side (orproximal side) of the tube 25. Also, the lengths of the hemisphericalcuts need not be the same. It may be advantageous to shorten one or theother side of the hemispherical cut based on a desired stiffnesscharacteristic for a particular application of the occluder. In analternative structure, the hemispherical cuts can be extended in a rangeup to 100% of the length of the distal side (or the proximal side) ofthe occluder, while still enabling the bow and twist of the struts.

As indicated previously and shown in FIGS. 2A-2H, distal side 30 andproximal side 40 of occluder 20 are connected by central tube 22. Thecentral tube 22 is formed by the portion of tube 25 between the distalside 30 of tube 25, which contains slits 31, (or 231) and the proximalside 40 of tube 25, which contains slits 41 (or 241). Given that thecentral portion of tube 25 remains uncut during the cutting process, thecentral portion of the tube maintains its profile upon the applicationof forces F_(d) and F_(p) and does not bow and twist outward as theproximal and distal sides are adapted to do.

According to one embodiment, central tube 22 is straight, as illustratedin FIGS. 2D and 2H, where the central tube 22 is perpendicular to loops32 and 42 (or 232 and 242). According to another embodiment of theinvention, central tube 22 is positioned at an angle θ relative to theproximal side 40 of the occluder 20, as shown, for example, in FIGS. 5Band 11. The shape of central tube 22 included in a given occluder is, atleast in part, determined by the nature of the aperture 18. An occluderhaving a straight central tube 22 is particularly suited to treat ananatomical anomaly including a perpendicular aperture, such as an ASDand certain PFOs. Often, however, anatomical anomalies, such as certainPFOs, have non-perpendicular apertures and are sometimes quitesignificantly non-perpendicular. An occluder having an angled centraltube 22 is well-suited for treatment of such defects, such that theangle of the anatomical aperture 18 is more closely matched by thepre-formed angle θ of the occluder 20. Also, the length of central tube22 can be varied depending on the anatomy of the defect being closed.Accordingly, the distal side 30 and proximal side 40 of occluder 20 aremore likely to be seated against and minimize distortion to the septaltissue 12 surrounding the aperture 18, as shown in FIG. 13. Awell-seated occluder 20 is less likely to permit blood leakage betweenthe right 11 and left 13 atria, and the patient into which the occluder20 has been placed is, therefore, less likely to suffer embolisms andother adverse events.

Advantageously, angled central tube 22 also facilitates delivery ofoccluder 20 because it is angled toward the end of the delivery sheath.In at least some embodiments, the angle θ is about 0-45 degrees. To formthe angle θ, proximal side 40 of the occluder 20 bends depending upon,among other factors, the material used to form occluder 20. Accordingly,depending upon design considerations, tip 44 and end 39 may be alignedwith central tube 22 or perpendicular to proximal side 40 or somevariation in between. One skilled in the art will be capable ofdetermining whether a straight or angled central tube 22 is best suitedfor treatment of a given anatomical aperture 18 and the appropriateangle θ, typically in the range between about 30 and about 90 degrees.Sometimes, angles of about 0 degrees to about 30 degrees can be used inan oblique passageway such as a very long tunnel PFO. One skilled in theart will recognize that the concept of an angled central tube may beapplied to septal occluders other than those disclosed herein.

When central tube 22 is positioned at angle θ, distal side 30 andproximal side 40 of occluder 20 may be configured such that they areeither directly opposing or, as shown in FIGS. 5B, 11 and 12, offset bydistance A. One skilled in the art will, of course, recognize that theshape and arrangement of either or both of distal side 30 and proximalside 40 may be adjusted such that the compressive forces they apply areas directly opposing as possible. However, in some clinicalapplications, an occluder 20 having an offset of distance A may beparticularly desirable. For example, as shown in FIGS. 5B, and 11-12, ifthe septal tissue 12 surrounding aperture 18 includes adisproportionately thick portion (e.g., septum secundum 16 as comparedto septum primum 14), the offset A may be used to seat occluder 20 moresecurely upon septal tissue 12. Moreover, the offset A allows each ofsides 30 and 40 to be centered around each side of an asymmetricaperture 18.

When a central tube 22 at angle θ is included in occluder 20, a markeris required to properly orient the occluder 20 in its intended in vivodelivery location. For example, a platinum wire may be wrapped aroundone of loops 32 or 42 (or one of loops 232 or 242) so as to permitvisualization of the orientation of the occluder 20 using fluoroscopy.Alternatively, other types of markers may be used, e.g., coatings,clips, etc. As one skilled in the art would appreciate, the radiopaquemarker could be blended in with the extrudate and thus providevisibility under fluoroscopy. As will be readily understood by oneskilled in the art, the orientation of a non-symmetrical occluder 20during delivery is of great importance. Of course, when anon-symmetrical occluder 20 is used, the periphery of the occluder 20may be configured such that the clamping force applied by the proximalside 40 is directly opposed to that applied by the distal side 30.

Upon deployment in vivo (a process described in detail below), anoccluder 20 according to the present invention applies a compressiveforce to the septal tissue 12. Distal side 30 is seated against theseptal tissue 12 in the left atrium 13, central tube 22 extends throughthe aperture 18, and proximal side 40 is seated against the septaltissue 12 in the right atrium 11. At least some portion of each of loops32 and 42 (or 232 and 242) contacts septal tissue 12. In particularembodiments, a substantial length of each of loops 32 and 42 (or 232 and242) contacts septal tissue 12. As illustrated in the representativeFigures, the proximal side 40 and distal side 30 of occluder 20 overlapsignificantly, such that the septal tissue 12 is “sandwiched” betweenthem once the occluder 20 is deployed. According to at least someembodiments and depending upon the material used to form occluder 20,the loops 32 and 42 (or 232 and 242) provide both a radially-extendingcompressive force and a circumferential compressive force to septaltissue 12. In these embodiments, the compressive forces are more evenlyand more widely distributed across the surface of the septal tissue 12surrounding the aperture 18 and, therefore, provide the occluder 20 withsuperior dislodgement resistance as compared to prior art devices. Asused in this application, “dislodgement resistance” refers to theability of an occluder 20 to resist the tendency of the force applied bythe unequal pressures between the right 11 and left 13 atria (i.e. the“dislodging force”) to separate the occluder 20 from the septal tissue12. Generally, a high dislodgement resistance is desirable.

Loops 32 and 42 (or 232 and 242) are also configured to minimize thetrauma they inflict on the septal tissue 12 surrounding aperture 18.Specifically, as indicated previously, the outer perimeter of loops 32and 42 (or 232 and 242) may be rounded.

According to one embodiment of the invention, for example, asillustrated in FIGS. 2B-2D, the circumferential portions of loops 32 and42 are thinner than the orthogonally-extending portions of loops 32 and42; therefore, the center of the occluder 20 is stronger than itsperimeter. Accordingly, outer perimeter of loops 32 and 42 of occluder20 has a low compression resistance. As used in this application,“compression resistance” refers to the ability of an occluder 20 toresist the lateral compressive force applied by the heart as itcontracts during a heartbeat. Generally, an occluder that resistscompressive force, i.e. has high compression resistance, is undesirablebecause its rigid shape and arrangement may cause trauma to the septaltissue 12, the right atrium 11, and/or the left atrium 13.

According to at least some embodiments of the present invention,occluder 20 further includes a catch system, generally indicated at 131,that secures the occluder 20 in its deployed state. The catch system131, in general, maintains the shape and arrangement of loops 32 and 42(or 232 and 242) of occluder 20, once the occluder 20 has been deployed.Catch system 131 reduces and maintains the axial length of the occluder20 so that occluder 20 maintains its deployed state, is secured in theaperture 18, and consistently applies a compressive force to septaltissue 12 that is sufficient to close aperture 18. Catch system 131 isparticularly advantageous when the occluder 20 is formed of a polymericmaterial, as previously described, because the polymeric occluder 20 maybe deformed during delivery such that it may not fully recover itsintended shape once deployed. By reducing and maintaining the axiallength of occluder 20 once it has been deployed in vivo, catch system131 compensates for any undesirable structural changes suffered byoccluder 20 during delivery. In some embodiments, catch system 131includes a ceramic material or a material selected from the groupconsisting of metals, shape memory materials, alloys, polymers,bioabsorbable polymers, and combinations thereof. In particularembodiments, the catch system may include nitinol or a shape memorypolymer. Further, the catch system may include a material selected fromthe group consisting Teflon-based materials, polyurethanes, metals,polyvinyl alcohol (PVA), extracellular matrix (ECM) or otherbioengineered materials, synthetic bioabsorbable polymeric scaffolds,collagen, and combinations thereof.

Catch system 131 may take a variety of forms, non-limiting examples ofwhich are provided in FIGS. 6A-6E. For example, as shown in FIG. 6A,catch system 131 includes two catch elements, e.g., balls, 133 and 135,connected by wire 134. The catch system and catch element are preferablymade of the same material as the occluder, although based on designselection, they could be made of the same or different material. Incertain circumstances, it may be necessary to make them of differentmaterial. As illustrated in FIG. 6A, delivery string 137 is attached toball 133 and is then extended through end 39, distal portion 30 of tube25, central tube 22, proximal portion 40 of tube 25, and tip 44, suchthat ball 133 is located between central tube 22 and end 39 and ball 135is located on the distal side of central tube 22. The function of catchsystem 131 is shown in FIGS. 6B-6E. Ball 133 is designed such that, uponthe application of sufficient pulling force F₁ to delivery string 137,it passes through central tube 22 (FIG. 6B) and tip 44 (FIG. 6C). Ball133 cannot reenter tip 44 or central tube 22 without the application ofa sufficient, additional force. In this manner, ball 133 may be used tobring together the distal side 30 and the proximal side 40, therebyreducing and maintaining the axial length of occluder 20. Obviously,during the application of pulling force F₁, the tip 44 of occluder 20must be held against an object, such as a delivery sheath. Ball 135 isdesigned such that, upon application of sufficient pulling force F₂ todelivery string 137, it passes through end 39 (FIG. 6D) and central tube22 (FIG. 6E). The pulling force F₂ required to move ball 135 through end39 and central tube 22 is greater than the pulling force F₁ required tomove ball 133 through central tube 22 and tip 44. However, ball 135cannot pass through tip 44. Thus, the application of sufficient pullingforce F₂ to ball 135 releases distal side 30 and proximal side 40, asdescribed in more detail below. It should be noted that while catchelements 133 and 135 are illustrated as spherical elements in FIGS.6A-6E, catch elements 133 and 135 may take any suitable shape. Forexample, catch elements 133 and 135 may be conical. The narrow portionsof conical catch elements 133 and 135 point toward tip 44 of proximalside 40. One possible mode of recovery or retrieval for this device issimply reversing the implantation procedure. Of course, other modes ofrecovery or retrieval are possible, some of which are described in thisspecification.

A different system for securing the device in the deployed state isshown in FIGS. 7A-7C. A locking mechanism 191 includes a hollow cylinder141 having at least two half-arrows 143 and 145 located at its proximalend (FIG. 7A). Cylinder 141 enters tip 44 under application of pullingforce F₁ to delivery string 137. As cylinder 141 enters tip 44,half-arrows 143 and 145 are forced together such that the diameter ofthe proximal end of cylinder 141 is reduced (FIG. 7C). Under continuedapplication of pulling force F₁, half-arrows 143 and 145 pass throughtip 44 and expand to their original shape and arrangement (FIG. 7B).Given that half-arrows 143 and 145 extend beyond the diameter of tip 44,the axial length of an occluder 20 including the locking mechanism 191shown in FIGS. 7A-7C is maintained in its reduced state. If the implantneeds to be removed or repositioned, the locking mechanism 191 shown inFIGS. 7A-7C may be released by moving half-arrows 143 and 145 togethersuch that the diameter of the proximal end of cylinder 141 is smallerthan that of tip 44 and cylinder 141 passes through tip 44. Cylinder 141may then be withdrawn from tip 44.

One skilled in the art will recognize that catch system 131 may assumenumerous configurations while retaining its capability to reduce andmaintain the axial length of occluder 20 such that occluder 20 maintainsits deployed state. For example, catch system 131 may include a threadedscrew, a tie-wrap, or a combination of catch systems 131. Furthermore,catch system 131 may include multiple members that may provide a steppeddeployment process. For example, catch system 131 as depicted in FIGS.6A-6E may include three balls. In this configuration, one ball is usedto secure the distal end 30 of occluder 20 and another ball is used tosecure the proximal end 40 of occluder 20, and the third ball is securedto the distal end. Any suitable catch system 131 may be incorporatedinto any of the embodiments of occluder 20 described herein. One skilledin the art will be capable of selecting the catch system 131 suitablefor use in a given clinical application.

Occluder 20 may be modified in various ways. According to someembodiments of the present invention, distal side 30 and/or proximal 40side of occluder 20 may include a tissue scaffold. The tissue scaffoldensures more complete coverage of aperture 18 and promotes encapsulationand endothelialization of septal tissue 12, thereby further encouraginganatomical closure of the septal tissue 12. The tissue scaffold may beformed of any flexible, biocompatible material capable of promotingtissue growth, including but not limited to polyester fabrics,Teflon-based materials, ePTFE, polyurethanes, metallic materials,polyvinyl alcohol (PVA), extracellular matrix (ECM) or otherbioengineered materials, synthetic bioabsorbable polymeric scaffolds,other natural materials (e.g., collagen), or combinations of theforegoing materials. For example, the tissue scaffold may be formed of athin metallic film or foil, e.g., a nitinol film or foil, as describedin United States Patent Publ. No. 2003/0059640 (the entirety of which isincorporated herein by reference). In those embodiments, where occluder20 includes a tissue scaffold, the scaffold may be located on theoutside the face of distal side 30 and proximal side 40 of the occluder,with an alternative of including scaffold also inside the face of distalside 30 and proximal side 40 of the occluder. Also, the tissue scaffoldcould be disposed against the tissue that is sought to be occluded, suchas the septal tissue 12 so that the proximity of the tissue scaffold andseptal tissue 12 promotes endothelialization. Loops 32 and 42, (or 232and 242), can be laser welded, ultrasonically welded, thermally welded,glued, or stitched to the tissue scaffold to securely fasten thescaffold to occluder 20. One skilled in the art will be able todetermine those clinical applications in which the use of tissuescaffolds and/or stitches is appropriate.

Occluder 20 may be further modified so that it lacks end 39 and tip 44,as shown in FIGS. 8A-8C, and, therefore, has a reduced septal profile.Such an occluder may be formed in several ways. For example, accordingto one embodiment, slits 31 and 41 are extended through end 39 and tip44, respectively, of tube 25 during the cutting process. This cuttingpattern produces struts 32 that deform during deployment to produceincomplete loops 32. One side of the device, facing the viewer as shownin FIG. 8A, is formed by slits 31 that extend along the tube 25 tovarying lengths. The tube 25 is cut in half to form half sections 154 aand 154 b. The half sections 154 a and 154 b are further cut to aproximal distance from the end 39 into quarter sections 155 a, 156 a,155 b, and 156 b. The ends of the quarter sections 155 a and 155 b arejoined at “free ends” 153 to close the loop 32. Similarly, the free endsof quarter sections 156 a and 156 b may be joined by appropriatecutting, see FIG. 8b . The ends may be joined using any suitableconnectors, e.g., 151, e.g., welds. One of skill in the art willrecognize that the free ends 153 of loops 32 may be connected usingother means, including but not limited to seams and bonds obtained byheat or vibration.

In the above embodiment, the slits in the quarter sections are runcompletely through the end of the tube 39. In an alternative embodiment,the end 39 may remain uncut, thereby eliminating the need for a weld tojoin the quarter sections together.

The embodiment illustrated in FIGS. 8A-8C depicts an occluder 20 inwhich both sides are formed according to the above-described design.Alternatively, an occluder 20 according to the present invention mayinclude a hybrid structure, wherein one side is designed according tothe embodiment shown in FIGS. 8A-8C and the other side is designedaccording to other types of structures disclosed in this application.

Occluder 20 may be prepared for delivery to an aperture 18 in any one ofseveral ways. Slits 31 and 41 (or 231 and 241) may be cut such that tube25 bends into its intended configuration following deployment in vivo.Specifically, slits 31 and 41 (or 231 and 241) may be cut to a thicknessthat facilitates the bending and formation of loops 32 and 42 (or 232and 242). Upon the application of forces F_(d) and F_(p), tube 25 bendsinto its intended deployed configuration. Alternatively and/oradditionally, tube 25 formed of a shape memory material may be preformedinto its intended configuration ex vivo so that it will recover itspreformed shape once deployed in vivo. According to at least someembodiments, these preforming techniques produce reliable deployment andbending of occluder 20 in vivo. An intermediate approach may also beused: tube 25 may be only slightly preformed ex vivo such that it ispredisposed to bend into its intended deployed configuration in vivoupon application of forces F_(d) and F_(p).

An occluder 20 as described herein may be delivered to an anatomicalaperture 18 using any suitable delivery technique. For example, distalside 30 and proximal side 40 of occluder 20 may be deployed in separatesteps, or both distal side 30 and proximal side 40 of occluder 20 may bedeployed in the same step. One delivery method will be described indetail herein.

As shown in FIGS. 9A-9H, a delivery sheath 161 containing pusher sleeve169 (shown in FIG. 9H) is used to deliver occluder 20 including thecatch system 131 illustrated in FIGS. 6A-6E. Sheath 161 containsoccluder 20 in its elongated, delivery form (FIG. 9A). As shown in FIG.9B, delivery sheath 161 is first inserted into the right atrium 11 ofthe patient's heart. Sheath 161 is next inserted through aperture 18located in the septal tissue 12 (which, in this example, is a PFOtunnel) and into the left atrium 13 (FIG. 9C). Distal side 30 ofoccluder 20 is then exposed into the left atrium 13, as shown in FIG.9D. Following deployment of distal side 30, pulling force F₁ is appliedto delivery string 137 while pusher sleeve 169 is holding the occluder20 in place such that ball 133 passes through the central tube 22,thereby securing distal side 30 into its deployed state (FIG. 9E).Sheath 161 is further withdrawn through the aperture 18 and into theright atrium 11, such that central tube 22 is deployed through theaperture 18 (FIG. 9F). Proximal side 40 of occluder 20 is then exposedinto the right atrium 11 (FIG. 9G), and pulling force F₁ is againapplied to delivery string 137 while pusher sleeve 169 is holding theoccluder 20 in place such that ball 133 passes through tip 44, therebysecuring the proximal side 40 into its deployed state (FIG. 9H). Whenproperly deployed, occluder 20 rests within the aperture 18, and thedistal side 30 and proximal side 40 exert a compressive force againstseptum primum 14 and septum secundum 16 in the left 13 and right 11atria, respectively, to close the aperture 18, i.e. the PFO. Whenoccluder 20 is properly deployed, delivery string 137 is detached fromcatch system 131, including balls 133 and 135 and a connecting member,and sheath 161 is then withdrawn from the heart. In the event occluder20 is not properly deployed after performing the procedure describedabove, the occluder 20 may be recovered by reversing the steps of theabove described delivery sequence.

In an alternative recovery technique, the occluder 20 may be recoveredand repositioned by catch system 131 as shown in FIGS. 10A-10D. Pushersleeve 169 in sheath 161 is positioned against tip 44 of the occluder 20in the right atrium 11 (FIG. 10A). Pulling force F₂ is applied todelivery string 137, such that ball 135 passes through end 39 and intocentral tube 22, thereby releasing distal side 30 from its deployedstate (FIG. 10B). Force F₂ is again applied to delivery string 137 sothat ball 135 subsequently passes through central tube 22, therebyreleasing proximal side 40 from its deployed state (FIG. 10C). Deliverystring 137 is then pulled further such that occluder 20, now in itselongated state, is retracted into sheath 161 (FIG. 10D). Followingrecovery of occluder 20, sheath 161 may be withdrawn from the heart andanother occluder inserted in the desired delivery location as describedabove and shown in FIGS. 9A-9H.

One skilled in the art will recognize that the occluders describedherein may be used with anti-thrombogenic compounds, including but notlimited to heparin and peptides, to reduce thrombogenicity of theoccluder and/or to enhance the healing response of the septal tissue 12following deployment of the occluder in vivo. Similarly, the occludersdescribed herein may be used to deliver other drugs or pharmaceuticalagents (e.g., growth factors, peptides). The anti-thrombogeniccompounds, drugs, and/or pharmaceutical agents may be included in theoccluders of the present invention in several ways, including byincorporation into the tissue scaffold, as previously described, or as acoating, e.g., a polymeric coating, on the tube(s) 25 forming the distalside 30 and proximal side 40 of the occluder 20. Furthermore, theoccluders described herein may include cells that have been seededwithin the tissue scaffold or coated upon the tube(s) 25 forming thedistal side 30 and proximal side 40 of the occluder 20.

One skilled in the art will further recognize that occluders accordingto this invention could be used to occlude other vascular andnon-vascular openings. For example, the device could be inserted into aleft atrial appendage or other tunnels or tubular openings within thebody.

Having described preferred embodiments of the invention, it should beapparent that various modifications may be made without departing fromthe spirit and scope of the invention, which is defined in the claimsbelow.

What is claimed is:
 1. An occluder device for occluding a defect in abody, the occluder device having a delivery configuration in which theoccluder device is adapted to be delivered through the body'svasculature and a deployed configuration in which the occluder device isadapted to occlude the defect, the occluder device comprising: a centraltube portion; a proximal side comprising a proximal end tube portion anda plurality of proximal struts, the plurality of proximal strutscomprising (i) a first proximal strut portion directly extending fromthe central tube portion, (ii) a second proximal strut portion directlyextending from the proximal end tube portion, and (iii) a proximalcircumferential strut portion extending between the first proximal strutportion and the second proximal strut portion, the proximal end tubeportion forming a first terminal end of the occluder device, wherein theproximal circumferential strut portion is thinner than the firstproximal strut portion, and wherein the proximal circumferential strutportion is thinner than the second proximal strut portion; and a distalside comprising a distal end tube portion and a plurality of distalstruts, the plurality of distal struts comprising (i) a first distalstrut portion directly extending from the central tube portion, (ii) asecond distal strut portion directly extending from the distal end tubeportion, and (iii) a distal circumferential strut portion extendingbetween the first distal strut portion and the second distal strutportion, the distal end tube portion forming a second terminal end ofthe occluder device, wherein the distal circumferential strut portion isthinner than the first distal strut portion, and wherein the distalcircumferential strut portion is thinner than the second distal strutportion, wherein, in the deployed configuration, the plurality ofproximal struts form a plurality of proximal loops that all liegenerally entirely within a proximal side plane and the plurality ofdistal struts form a plurality of distal loops that all lie generallyentirely within a distal side plane, and wherein the central tubeportion is positioned at an angle with respect to the proximal anddistal side planes.
 2. The occluder device according to claim 1, whereinthe plurality of proximal loops are of different diameter than theplurality of distal loops.
 3. The occluder device according to claim 1,wherein the plurality of proximal struts are radially offset withrespect to the plurality of distal struts.
 4. The occluder deviceaccording to claim 1, further comprising a catch system adapted tosecure the occluder device in the deployed configuration and to notsecure the occluder device in the delivery configuration.
 5. Theoccluder device according to claim 4, wherein the catch system comprisesone or more catch elements that cooperate with one or more passagewayswithin the occluder device such that occluder device becomes secured inthe deployed configuration by compressive forces exerted by the one ormore catch elements on the proximal end tube portion and the distal endtube portion when the proximal side and the distal side are positionedbetween the one or more catch elements.
 6. The occluder device accordingto claim 5, wherein the catch system comprises two catch elements thatare connected to each other by a wire or a string.
 7. The occluderdevice according to claim 1, further comprising a locking member thatincludes at least two locking pieces adapted to hold the occluder devicein the deployed configuration when the locking pieces cooperate with thecentral tube portion or the proximal end tube portion.
 8. The occluderdevice according to claim 1, wherein each of the plurality of proximalloops and the plurality of distal loops twist when the occluder devicetransitions from the delivery configuration to the deployedconfiguration.
 9. The occluder device according to claim 1, wherein theangle between the central tube portion and the proximal and distal sideplanes is non-perpendicular.
 10. The occluder device according to claim1, further comprising tissue scaffolding attached to the plurality ofproximal loops or the plurality of distal loops.
 11. The occluder deviceaccording to claim 10, wherein the tissue scaffolding is a bioresorbablematerial.
 12. The occluder device according to claim 1, wherein theoccluder device comprises a bioresorbable material.
 13. The occluderdevice according to claim 1, wherein the occluder device comprisesnitinol.
 14. The occluder device according to claim 1, wherein theplurality of proximal loops and the plurality of distal loops areunequal in terms of their respective numbers of loops.
 15. The occluderdevice according to claim 1, wherein the angle between the central tubeportion and the proximal and distal side planes is in a range of about 0degrees to about 45 degrees.
 16. An occluder device for occluding adefect in a body, the occluder device having a delivery configuration inwhich the occluder device is adapted to be delivered through the body'svasculature and a deployed configuration in which the occluder device isadapted to occlude the defect, the occluder device comprising: aproximal end tube portion, a central tube portion defining a tube havinga sidewall, a proximal end that is open and, a distal end that is open,and a distal end tube portion, each of the proximal end tube portion,the central tube portion, and the distal end tube portion having an openinterior configured for allowing passage of a member therethrough; aproximal side comprising a plurality of proximal struts, each of theplurality of proximal struts comprising (i) a first proximal strutportion extending from the proximal end of the central tube portion,(ii) a second proximal strut portion extending from the proximal endtube portion, and (iii) a proximal circumferential strut portionextending between the first proximal strut portion and the secondproximal strut portion; and a distal side comprising a plurality ofdistal struts, each of the plurality of distal struts comprising (i) afirst distal strut portion extending from the distal end of the centraltube portion, (ii) a second distal strut portion extending from thedistal end tube portion, and (iii) a distal circumferential strutportion extending between the first distal strut portion and the seconddistal strut portion, wherein the proximal end tube portion, theproximal side, the central tube portion, the distal side, and the distalend tube portion forming a monolithic structure such that in thedelivery configuration the occluder device defines a substantiallytubular structure, and in the deployed configuration, the plurality ofproximal struts form a plurality of proximal loops that all liegenerally entirely within a proximal side plane and the plurality ofdistal struts form a plurality of distal loops that all lie generallyentirely within a distal side plane, wherein each of the plurality ofproximal loops defines an opening parallel to a longitudinal axis of theoccluder device, and wherein each of the plurality of distal loopsdefines an opening parallel to the longitudinal axis of the occluderdevice.
 17. The occluder device according to claim 16, wherein themember is a locking member configured to hold the occluder device in thedeployed configuration, and at least one of the proximal end tubeportion, the central tube portion, and the distal end tube portion isconfigured to pass the locking member therethough.
 18. The occluderdevice according to claim 16, wherein the member is a wire, and the openinterior of each of the proximal end tube portion, the central tubeportion, and the distal end tube portion is configured to pass the wiretherethrough.
 19. The occluder device according to claim 18, furthercomprising a wire passing through the open interior of at least one ofthe proximal end tube portion, the central tube portion, and the distalend tube portion.
 20. The occluder device according to claim 16, whereinthe plurality of distal struts deploy to radially overlap in an areaformed by the distal side and the plurality of proximal struts deploy toradially overlap in an area formed by the proximal side.
 21. An occluderdevice for occluding a defect in a body, the occluder device having adelivery configuration in which the occluder device is adapted to bedelivered through the body's vasculature and a deployed configuration inwhich the occluder device is adapted to occlude the defect, the occluderdevice comprising: a proximal end tube portion, a central tube portiondefining a tube having a sidewall, a proximal end that is open and, adistal end that is open, and a distal end tube portion, each of theproximal end tube portion, the central tube portion, and the distal endtube portion having an open interior configured for allowing passage ofa member therethrough; a proximal side comprising a plurality ofproximal struts, each of the plurality of proximal struts comprising (i)a first proximal strut portion extending from the proximal end of thecentral tube portion, (ii) a second proximal strut portion extendingfrom the proximal end tube portion, and (iii) a proximal circumferentialstrut portion extending between the first proximal strut portion and thesecond proximal strut portion; and a distal side comprising a pluralityof distal struts, each of the plurality of distal struts comprising (i)a first distal strut portion extending from the distal end of thecentral tube portion, (ii) a second distal strut portion extending fromthe distal end tube portion, and (iii) a distal circumferential strutportion extending between the first distal strut portion and the seconddistal strut portion, wherein the proximal end tube portion, theproximal side, the central tube portion, the distal side, and the distalend tube portion forming a single piece such that in the deliveryconfiguration the occluder device defines a substantially tubularstructure, and in the deployed configuration, the plurality of proximalstruts form a plurality of proximal loops that all lie generallyentirely within a proximal side plane and the plurality of distal strutsform a plurality of distal loops that all lie generally entirely withina distal side plane, wherein each of the plurality of proximal loopsdefines an opening parallel to a longitudinal axis of the occluderdevice, and wherein each of the plurality of distal loops defines anopening parallel to the longitudinal axis of the occluder device. 22.The occluder device according to claim 21, wherein the member is alocking member configured to hold the occluder device in the deployedconfiguration, and at least one of the proximal end tube portion, thecentral tube portion, and the distal end tube portion is configured topass the locking member therethrough.
 23. The occluder device accordingto claim 21, wherein the plurality of distal struts deploy to radiallyoverlap in an area formed by the distal side and the plurality ofproximal struts deploy to radially overlap in an area formed by theproximal side.